1. Field
The present disclosure relates to a semiconductor device, and an inverter, a converter and a power conversion device employing the semiconductor device. In particular, the present disclosure relates to a semiconductor device having a high breakdown voltage transistor, and an inverter, a converter and a power conversion device employing the semiconductor device.
2. Description of the Related Art
Power conversion devices of relate art employ a high breakdown voltage transistor. There is also a method of using multiple high breakdown voltage transistors connected in parallel to allow a power conversion device to have an increased rated current. This method is intended to control the concentration of current on a high breakdown voltage transistor having a lower threshold voltage from among multiple high breakdown voltage transistors. To this end, a current flowing through each high breakdown voltage transistor is detected. When a difference between the currents of the multiple high breakdown voltage transistors becomes higher than a predetermined value, the resistance value of a gate resistor is configured to be lower than a standard value to turn on the multiple transistors earlier. Related art technique is disclosed Japanese Unexamined Patent Application Publication No. 2002-95240, for example.
The power conversion device of related art suffers from variations in turn-on time caused by variations in the threshold voltage of the high breakdown voltage transistors. Variations in the performance of the power conversion device thus result.
The method described in Japanese Unexamined Patent Application Publication No. 2002-95240 uses as many current sensors as the high breakdown voltage transistors, each gate resistor configured to be a variable resistor, and a controller to control resistance of the variable resistor on the basis of the detection result of the current sensor. Accordingly, the configuration of the device is complicated, resulting in high costs.